MASS SELECTION Mass selection is a method of breeding in which individual plants are selected on the basis of phenotype from a mixed population , their seeds are bulked and used to grow the next generation. Selection cycle may be repeated one or more times to increase the frequency of favorable alleles - phenotypic recurrent selection. PURELINE SELECTION A pureline is the progeny of a single homozygous plant of a self-pollinated species. All the plants in a pureline have the same genotype and the phenotypic variation within a pureline is due to the environment alone and has no genetic basis. However, variation within a pureline is not heritable. Hence selection in a pureline is not effective. Johannsen (1903,1926), a Danish biologist, developed the concept of pureline theory working with Princess variety of French bean (Phaseolus vulgaris), which showed variation for seed size. From a commercial seed lot he selected seeds of different sizes and grew them separately. The progenies differed in seed size. Progenies from larger seeds produced larger seeds than those obtained from smaller seeds. This clearly showed that the variation in seed size in the commercial seed lot of princess variety had a genetic base. As a result selection for seed size was effective. Introduction PEDIGREE SELECTION Pedigree selection is a widely used method of breeding self-pollinated species. A key difference between pedigree selection and mass selection or pure-line selection is that hybridization is used to generate variability (for the base population), unlike the other methods in which production of genetic variation is not a feature. The method was first described by H. H. Lowe in 1927. Pedigree selection is a breeding method in which the breeder keeps records of the ancestry of the cultivar. The base population is established by crossing selected parents, followed by handling an actively segregating population. Documentation of the pedigree enables breeders to trace parent–progeny back to an individual F2 plant from any subsequent generation. The breeder should develop an effective, easy to maintain system of record keeping. Pedigree selection is applicable to breeding species that allow individual plants to be observed, described, and harvested separately.

1. SELECTION METHODS IN SELF-
POLLINATED CROPS
viz., mass selection, pureline selection & pedigree selection
Submitted to:
Dr. (Mrs) Vedna Kumari
Submitted by:
Amit Rana
A-2019-40-013

2. MASS SELECTION

3. INTRODUCTION
 As an ancient art, farmers saved seed from desirable plants for planting the next season’s crop, a practice
that is still common in the agriculture of many developing countries.
 Mass selection is often described as the oldest method of breeding self-pollinated plant species. It has been
used widely to improve old “land” varieties, varieties that have been passed down from one generation of
farmers to the next over long periods.
 An alternative approach that has no doubt been practiced for thousands of years is simply to eliminate
undesirable types by destroying them in the field.
 The results are similar whether superior plants are saved or inferior plants are eliminated: seeds of the
better plants become the planting stock for the next season.
 Mass selection is a method of breeding in which individual plants are selected on the basis of phenotype
from a mixed population , their seeds are bulked and used to grow the next generation.

4. INTRODUCTION
 This method of selection is applicable to both self- and cross-pollinated species. But it is more used for
cross-pollinated crops.
 Selection cycle may be repeated one or more times to increase the frequency of favorable alleles -
phenotypic recurrent selection.
 Selection is now based not solely on the appearance of the parent plants but also on the appearance and
performance of their progeny. However, that progeny testing requires an extra generation; hence gain per
cycle of selection must be double that of simple phenotypic selection to achieve the same rate of gain per
unit time.
 Mass selection, with or without progeny test, is perhaps the simplest and least expensive of plant-breeding
procedures. It finds wide use in the breeding of certain forage species, which are not important enough
economically to justify more detailed attention.
 Progeny selection is usually more effective than phenotypic selection when dealing with quantitative
characters of low heritability.
 A modern refinement of mass selection is to harvest the best plants separately and to grow and compare
their progenies. The poorer progenies are destroyed and the seeds of the remainder are harvested.

5. - - - - - - - - -
- - - - - - - - -
- - - - - - - - -
i) Several plants selected on
the basis of phenotype
ii) Open pollinated seeds
from the selected plants
harvested & bulked
1st year
First selection
cycle
- - - - - - - - -
- - - - - - - - -
- - - - - - - - -
2nd year
Second
selection cycle
i) Bulk seed from the selected plants
grown
ii) Mass selection may be repeated
Repeat the selection cycle if
sufficient gain is not there
Selection without Progeny Testing
Yield
trials

6. KEY FEATURES
 The purpose of mass selection is population improvement through increasing the gene frequencies of desirable
genes.
 Selection is based on plant phenotype and one generation per cycle is needed.
 Mass selection is imposed once or multiple times (recurrent mass selection).
 The improvement is limited to the genetic variability that existed in the original populations.
 The goal in mass selection is to improve the average performance of the base population.
 The success of mass selection mainly depends on these factors: Variability in the base population, mode of
inheritance of the character to be improved, number of genes involved , additive gene action and heritability of
the character.

7. TYPES OF MASS SELECTION
1. Positive mass selection:
 Desirable plants are selected from a mixed population.
 Base material is old varieties or land races.
2. Negative mass selection
 Undesirable off type plants are removed from a mixed population.
 used for varietal purification in seed production and certification programs.

8. APPLICATIONS
1. Improvement of Desi or local variety
 The local varieties are mixtures of several genotypes, which may differ in flowering or maturity plant height, disease
resistant etc.
 Many of these plants type would be inferior and low yielding, such plants will be eliminated through mass selection
and local variety would be improved without adversely affecting its adaptability and stability.
 Because the new variety would be made up of the most of the superior plants type present in the original local variety.
2. Purification the existing pure line variety
 Pure lines tend to become variable with time due to mechanical mixtures, natural hybridization, mutation etc.
therefore, it is necessary that the purity of pure line varieties be maintained through regular mass selection.
 Mass selection is generally important and practiced in cross-pollinated crop and has the only limited application in self
pollinated crop.

9. APPLICATIONS
 It may be used to maintain the purity of an existing cultivar that has become contaminated.
 It can also be used to develop a cultivar from a base population created by hybridization.
 It may be used to preserve the identity of an established cultivar or soon to be released new
cultivar.
 Some breeders use mass selection as part of their breeding program to rogue out undesirable
plants, thereby reducing the materials advanced and saving time and reducing costs of breeding.

10. CULTIVAR DEVELOPMENT PROCEDURE
X

11. PURIFICATION OF AN EXISTING CULTIVAR

12. MERITS
 Since a large number of plants are selected the adoption of the
original variety is not changed. It is generally accepted that a mix
of closely related pure lines is more stable in performance over
different environment than a single pure line. Thus varieties
developed through mass selection are more widely adapted than
pure lines.
 Often extensive and prolonged yield trials are not necessary. This
reduces the time and cost needed for developing a new variety.
 It is a less demanding method. The breeder can devote more time
to other breeding programmes.
 The varieties developed through mass selection show variation and
are not as uniform as pure line varieties.
 The improvement through mass selection is generally less than they
through pure line selection.
 In the absence of progeny test, it is not possible to determine if the
selected plants are homozygous.
 Due to popularity of pure line varieties, mass selection is not
commonly used in improvement of self palliated crops. But it is
quick and convenient method of improving old local variety in the
areas or crop spp where crop improvement has just begun.
 Varieties developed by mass selection are more difficult to identify
than pure line in seed certification programme.
DE-MERITS

13. DEFECTS IN MASS SELECTION
1. Lack of control on the pollen source
2. Lack of information on progeny performance
3. The confusing effect of environment on phenotypes of individual plants

14. MODIFICATIONS OF MASS SELECTION
1. Rejection of inferior pollen: Inferior plants are detassled and remaining are allowed to open
pollinate
2. Composite Pollen: Pollen from all the selected plants is collected & bulked, this pollen is
used to pollinate the selected plants
3. Stratified Mass Selection
4. Contiguous control

15. STRATIFIED MASS SELECTION
 Suggested by Gardner (1961) and also known as the grid method of mass selection
 field from which selection is to be done is divided into several small plots having 40-50
plants/plot
 Equal number of superior plants are selected from each of the plots
 seed from selected plots is bulked to raise the next generation
 variation due to the environment, including heterogeneity in soil fertility, will be much
smaller within the small plots than in the whole field

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17. CONTIGUOUS CONTROL
1. Single cross hybrid/inbred are planted as checks after every 2-4 plants of the variety
under selection
2. Detassled the check plants.
3. Allow open pollination.
4. Compare the yield with nearest check

18. PURELINE SELECTION

19. INTRODUCTION
 A pureline is the progeny of a single homozygous plant of a self-pollinated species. All the plants in a pureline
have the same genotype and the phenotypic variation within a pureline is due to the environment alone and has
no genetic basis. However, variation within a pureline is not heritable. Hence selection in a pureline is not
effective.
 Johannsen (1903,1926), a Danish biologist, developed the concept of pureline theory working with Princess
variety of French bean (Phaseolus vulgaris), which showed variation for seed size.
 From a commercial seed lot he selected seeds of different sizes and grew them separately. The progenies differed
in seed size. Progenies from larger seeds produced larger seeds than those obtained from smaller seeds. This
clearly showed that the variation in seed size in the commercial seed lot of princess variety had a genetic base.
As a result selection for seed size was effective.

20. ORIGIN OF VARIATION IN PURE LINES
Pure lines show genetic variation after some time because of the following reasons;
1. Mechanical Mixture : During cultivation, harvesting threshing and storage, other genotypes
may get mixed up.
2. Natural hybridization: Through pure lines are produced in self pollinated crops, some
amount of natural cross pollination occurs in them also can be avoided by isolation and
rouging.
3. Mutation: occur spontaneously in nature at random

21. THE PROGENY TEST
Evaluation of the worth of plants on the basis of performance of their progenies is known
as progeny test. This was developed by Louis de Vilmorin and so it is also known as the
Vilmorin Isolation principle. Vilmorin worked on sugar beat plants. The progeny test
serves two valuable function;
1. Determines the breeding behavior of a plant i.e. whether it is homozygous or
heterozygous.
2. Whether the character for which the plant was selected is heritable i.e. is due to
genotype or not. Selections have to be based or phenotype and so it is necessary to
know the genotype of the selected plant.

22. PURE-LINE SELECTION-STEPS
1. Select desirable plants
 Number depends on variation of original population, space and resources for following
year progeny tests
 Selecting too few plants may risk losing superior genetic variation
 A genotype missed early is lost forever
2. Seed from each selection is harvested individually

23. PURE-LINE SELECTION-STEPS (CONT.)
3. Single plant progeny rows grown out.
 Evaluate for desirable traits and uniformity
 Should use severe selection criteria (rogue out all poor, unpromising and variable progenies)
4. Selected progenies are harvested individually.
5. In subsequent years, run replicated yield trials with selection of highest yielding plants.
6. After 4-6 rounds, highest yielding plant is put forward as a new cultivar.

25. KEY FEATURES
 A pure line consists of progeny descended solely by self-pollination from a single homozygous plant
 Pure line selection is therefore a procedure for isolating pure line(s) from a mixed population
 All the plants within a pureline have the same genotype.
 The variation within a pureline is environmental and non-heritable.
 Purelines are stable.
 A pure line suggests that a cultivar has identical alleles at all loci.
 Even though plant breeders may make this assumption, it is one that is not practical to achieve in a breeding
program.
 Line cultivars have a very narrow genetic base and tend to be uniform in traits of interest.
 In cases of proprietary dispute, lines are easy to unequivocally identify.

26. APPLICATIONS
Pure-line breeding is desirable for developing cultivars for certain uses:
 Cultivars for mechanized production that must meet a certain specification for uniform
operation by farm machines.
 Cultivars developed for a discriminating market that puts a premium on visual appeal
(e.g., uniform shape, size).
 Cultivars for the processing market (e.g., demand for certain canning qualities).
 Advancing that appear in a population (e.g., a mutant flower for ornamental use).
 Improving newly domesticated crops that have some variability.

27. ADVANTAGES
 It is a rapid breeding method.
 The method is inexpensive to conduct.
 The variety developed by this method has great “eye
appeal” because of the high uniformity.
 It is applicable to improving traits of low heritability,
because selection is based on progeny performance.
 Only the best pureline is selected for maximum
genetic advance.
DISADVANTAGES
 The purity of the variety may be altered through
admixture, natural crossing with other varieties and
mutations.
 Narrow genetic base and so poor adaptability.
 A new genotype is not created.
 The method promotes genetic erosion
 Progeny rows take up more resources (time, space).
 Only applicable to self pollinated species.

28. ?
How long will a cultivar remain pure?
1. As long as the commercial life of the cultivar, unless:
 Seed becomes contaminated with seed from other sources (e.g. from harvesting and seed cleaning
equipment)
 Natural out-crossing occurs (amount varies by species but seldom exceeds 1-2% in self-pollinated crops)
 Mutations occur
2. To maintain purity, off-types arising from mutation or out-crossing must be rogued out

29. 22
MASS SELECTION VS PURE LINE SELECTION
Single plant offsprings
L1 L2 L3……. LN
Register and market
the best pure lines
Line mixture
Mass selection Pure line selection
Bulk of
phenotypically
similar plants
Cultivar register
and marketing
Heterogenous cultivars Homogenous cultivars

30. PEDIGREE SELECTION

31. INTRODUCTION
 Pedigree selection is a widely used method of breeding self-pollinated species.
 A key difference between pedigree selection and mass selection or pure-line
selection is that hybridization is used to generate variability (for the base
population), unlike the other methods in which production of genetic variation is
not a feature.
 The method was first described by H. H. Lowe in 1927.

32. INTRODUCTION
 Pedigree selection is a breeding method in which the breeder keeps records of the ancestry of the
cultivar.
 The base population is established by crossing selected parents, followed by handling an actively
segregating population.
 Documentation of the pedigree enables breeders to trace parent–progeny back to an individual
F2 plant from any subsequent generation.
 The breeder should develop an effective, easy to maintain system of record keeping.
 Pedigree selection is applicable to breeding species that allow individual plants to be observed,
described, and harvested separately.

34. MERITS
 Record keeping provides a catalog of genetic
information of the cultivar.
 Selection is based not only on phenotype but also
on genotype (progeny row).
 Using the records, the breeder is able to advance
only the progeny lines in which plants that carry
the genes for the target traits occur.
 A high degree of genetic purity is produced in the
cultivar.
 Record keeping is slow, tedious, time-consuming,
and expensive.
 The method is not suitable for species in which
individual plants are difficult to isolate and
characterize.
 Pedigree selection is a long procedure, requiring
about 10–12 years or more to complete, if only one
growing season is possible.
 It is not effective for accumulating the number of
minor genes needed to provide horizontal
resistance.
DE-MERITS

35. THANK YOU